I've swapped a salvage yard engine into my '03, but I can't get it to fire. I have spark (I've seen one of the plug wires arc strongly). I think I have fuel, the plugs look wet and if I push the schrader valve on the back of the fuel rail, it has fuel pressure.

One odd thing is happening....the idle air bypass valve hums very loudly after the engine unsuccessfully cranks. It keeps humming until I turn the key off. Don't know if that has anything to do with it or not.

Any suggestions on how to properly troubleshoot my starting problem?

 

Just because you have fuel at the rail does not mean that the injectors are not plugged. If you are sure you have spark then go down the list; fuel, air. You should at least still have it stumble to try to start if it is trying to get air.

 

Right, but how do you make sure it's getting air and fuel? Just in case the idle air bypass valve is the culprit, I pulled the hose off the downstream side of the valve (i.e. the upper intake had direct access to air without going through the throttle body or bypass valve). That didn't seem to do anything. How can I see if fuel is actually making it into the cylinders other than pulling plugs and seeing if they're damp (which they seem to be)?

The only other thing I can think of that might be causing problems is the crank position sensor. I had to swap it over to the salvage yard engine as well as the flywheel and torque plate. I don't think there is a way to do that incorrectly (i.e. if I remember correctly, the flywheel had a locating pin, so it can't be oriented incorrectly).

 

BTW, the injectors came off the previous motor and were working when they were removed....so that seems like an unlikely problem.

 

Your plugs are wet so you are getting fuel. (injectors working)
Your plugs are sparking so you have spark. (crank sensor good)
Try pushing the gas pedal half way to the floor and then starting it and see what happens.
With the idle air control humming it sounds like it is bad, that is what give the engine air at idle, if it does not work it will not idle.

 

Having the same issues with my 2000 Disco, I have fuel pressure and spark and the idle air control is humming and car doesn't start. The car seems to be trying to start with a piston or two firing but doesn't start. If the idle air control is bad will it start but not idle or just not start? It is a 2000 Disco. I replaced engine last summer was running well until last week just didn't start one cold morning, tried dry gas then towed to mechanic he found one code forgot number but he described as a 'can' code dealing with the computers interfacing he's looking for a short somewhere.

 

Hmm, the weird thing about the idle air control valve is that I swapped one off an extra motor, and it did the same thing. Plus, if that was the starting problem, wouldn't unhooking the hose (like I did) remedy the problem temporarily?

Spike - I've tried the gas pedal in multiple positions (halfway, on the floor, etc.). During one start attempt with the idlle air hose unhooked, it did backfire through the house...yet another indication of spark and fuel. This is frustrating!

 

Really fustrating, I had just put in new power steering pump and two days later it doesn't start. Like I said I towed mine to my mechanic and he thinks a short or some wires chaffed or something since fuel pressure and spark check out. This is the time of year I'ld like to use the Rover the most and it seems to always crap out on me.

 

I hear ya. I'll keep trying a few things on mine...but after that, my next move is probably the same as yours was - tow it to a shop and have it checked out.

Just re-read your post Spike. That's good to know that spark indicates that the CPS is working.

 

I hate to be to simplistic, but I would pull a couple of the plugs and use some starting fluid. See if it kicks. Then I would go back to the start with the pul wires. Most of the time these things are something easy that I just went to fast with. All you need is spark, air and fuel, Thats the game. If they all exist its timing.